Unterrainer, R. N., Gambino, D., Bodenseher, A., Semper, F., Torsello, D., Laviano, F., & Eisterer, M. (2023, November 14). Impact of neutron induced ex-situ defects on the properties of CCs and their thermal stability [Conference Presentation]. IREF 2023 - Irradiation Effects on HTS for Fusion, Arona, Italy, Italy. https://doi.org/10.34726/5456
E141-06 - Forschungsbereich Low Temperature Physics and Superconductivity
IREF 2023 - Irradiation Effects on HTS for Fusion
12-Nov-2023 - 16-Nov-2023
Arona, Italy, Italy
high temperature superconductors; ybco; gdbco; coated conductors; fusion; neutron irradiation; frenkel pairs; radiation resistance
Fusion will produce high energy neutrons at 14 MeV, which, with a broadened spectrum due to scattering, will introduce various defects into the conductor of the superconducting magnets. The lifetime of the coils will mainly be restricted by the neutron flux and thus their distance to the burning plasma. While the price of energy output by large reactor designs will mainly be defined by the price of
the initial construction, the expected short lifetime of superconducting magnets might drive the cost in small designs as e.g. SPARC and STEP. Since the price of energy needs to be competitive in order for fusion to be economically feasible, mitigation strategies have to be developed. This however, requires a deep understanding of the underlying degradation processes.
Samples based on commercial coated conductors containing YBCO and GdBCO were irradiated with neutrons at approximately 70 °C in our fission reactor TRIGA MARK II to introduce comparable defects and study the behavior of the critical current, the n-value and the critical temperature. Samples containing GdBCO showed a fundamentally different degradation behavior, if irradiated with a neutron
spectrum containing particle energies below 0.55 eV. We attribute the behavior to the formation of a high density of almost point-like defects, induced by the high absorption cross section of Gadolinium to thermal neutrons. The Gadolinium nucleus enters an excited state after the absorption of a thermal
neutron. This state decays by the emission of a gamma particle that leads to the recoil of the Gd atom and in consequence to a high density of Oxygen defects. Data from molecular dynamics simulations indicate that, due to its position in the REBCO lattice, some of the formed defects are located in the Cu-O
plains, which could have a strong impact on the superconducting properties.
These very specific defects allow us to distinguish the influence of small versus large defective structures on the superconducting properties of REBCO. In further consequence fundamentally different defect structures are expected to be stable up to different temperatures enabling a study of the capability of heat treatments to recover neutron induced degradation
TRIGA Mark II-Nuklearreaktor
High-temperature superconducting materials for fusion magnets. The partner project is KKKÖ ME: 0000000000 (European Commission)
Special and Engineering Materials: 80% Sustainable Production and Technologies: 20%